Cluster of differentiation 44 and Receptor for hyaluronan-mediated motility (CD44/RHAMM)

Cluster of differentiation 44 (CD44) and the Receptor for hyaluronan-mediated motility (RHAMM, also known as CD168) are the two primary cell surface receptors for hyaluronan (HA), a key glycosaminoglycan in the extracellular matrix [1][2]. CD44 is a transmembrane glycoprotein that exists in multiple isoforms due to alternative splicing, while RHAMM is a multifunctional protein that can localize to the cell surface, cytoplasm, or nucleus [3][12]. These receptors often cooperate to form signaling complexes, such as the CD44/RHAMM/ERK1/2 axis, which regulates critical cellular processes including motility, invasion, proliferation, and survival [4][17]. In physiological conditions, they are essential for wound healing, tissue remodeling, and immune cell trafficking [1][10]. However, their overexpression is a hallmark of many cancers and inflammatory diseases, where they promote tumor progression, metastasis, and chronic inflammation [2][5][18]. Therapeutic targeting of this axis involves monoclonal antibodies, peptides, and vaccines designed to block HA binding or disrupt downstream signaling, though challenges remain regarding the widespread expression of CD44 in normal tissues and the context-dependent roles of these proteins [12][15].

Other names

Cluster of differentiation 44 (CD44)Receptor for hyaluronan-mediated motility (RHAMM)CD168HMMRHCELLPgp-1Phagocytic glycoprotein 1Extracellular matrix receptor III (ECMR-III)Hyaluronate receptorIntracellular hyaluronan-binding protein (IHABP)

Drugs targeting the CD44/RHAMM axis primarily act by blocking the interaction between hyaluronan (HA) and its receptors, thereby inhibiting downstream signaling pathways such as ERK1/2, MAPK, and Akt [1][3][12]. This is achieved through monoclonal antibodies that neutralize the receptors, competitive peptides that mimic HA-binding motifs, or small molecules that inhibit the synthesis of the HA ligand itself [7][12][15]. Additionally, antibody-drug conjugates (ADCs) utilize specific CD44 variants as docking sites for the targeted delivery of cytotoxic agents to tumor cells [1][13].